How Safe is DALK?

Newly developed corneal transplant techniques may result in poorer patient outcomes than older methods, according to a recent study published in the February 2014 Ophthalmology.

Researchers collected data from the Australian Corneal Graft Registry, established in 1985 to record the outcomes of corneal transplants performed nationally, and compared both graft survival and visual outcomes between patients who had penetrating keratoplasty, endokeratoplasty and deep anterior lamellar keratoplasty (DALK).

The data collected in the observational, prospective cohort study included 13,920 penetrating keratoplasties, 2,287 endokeratoplasties and 858 DALKs performed between January 1996 and February 2013.

According to the study, both graft survival (p<0.001) and visual outcome (p<0.001) were statistically better in patients who had penetrating keratoplasties than in those who received DALK.

Additionally, patients with Fuchs’ dystrophy who received penetrating keratoplasties experienced better graft survival (p<0.001) and visual outcomes (p<0.001) than those who had endokeratoplasties.

“This study’s conclusion that lamellar corneal surgery achieves inferior outcomes as compared to the traditional full-thickness penetrating keratoplasty is based on life expectancy of the transplant and visual outcomes,” says Eric Donnenfeld, MD, president of the American Society of Cataract and Refractive Surgery. But he doesn’t believe these parameters tell the whole story.

“Penetrating keratoplasty is associated with a mean of five diopters of astigmatism and anisometropia,” Dr. Donnenfeld says, “a risk of severe visual loss due to trauma approaching 1% and a dramatically higher incidence of glaucoma.” Additionally, the study makes no mention of how the patients achieved their reported vision (i.e., via GP lenses or spectacles).

While the results suggest that graft survival in DALK and endokeratoplasty procedures is worse than that of penetrating keratoplasties with the same indications over the same timeframe, the researchers also note that more lamellar procedures are being performed every year.

“I agree that an interface associated with lamellar surgery will reduce best-corrected visual acuity by zero to two lines of vision,” says Dr. Donnenfeld. He also notes that graft expectancy may be reduced, but the benefits of DALK make it a very reliable procedure overall.

“The dramatic increase in safety, speed of visual rehabilitation, reduced astigmatism and ease of repeat surgery make lamellar surgery the procedure of choice for most patients who have an option,” Dr. Donnenfeld concludes.